Computing devices such as personal computers, laptop computers, tablet computers, cellular phones, and countless types of Internet-capable devices are increasingly prevalent in numerous aspects of modern life. As computers become more advanced, augmented-reality devices, which blend computer-generated information with the user's perception of the physical world, are expected to become more prevalent.
To provide an augmented-reality experience, location and context-aware computing devices may be worn by a user as they go about various aspects of their everyday life. Such computing devices, which are commonly referred to as “wearable” computers, are configured to sense and analyze a user's environment, and to intelligently provide information appropriate to the physical world being experienced by the user.
Wearable computers may sense a user's surrounding by, for example, determining a user's geographic location, using cameras and/or sensors to detect objects near to the user, using microphones and/or sensors to detect what a user is hearing, and using various other sensors to collect information about the environment surrounding the user. Further, wearable computers may use biosensors detect the user's own physical state. The information collected by the wearable computer may then be analyzed in order to determine what information should be presented to the user.
Many wearable computers include or take the form of a head-mounted display (HMD) that is worn by the user. An HMD typically provides a heads-up display near to the user's eyes. As such, HMDs may also be referred to as “near-eye” displays. HMDs may overlay computer-generated graphics (e.g., text, images, video, etc.) on the physical world being perceived by the user. HMDs that include displays in front of both of the user's eyes are referred to as “binocular” HMDs, while those that include a display in front of just one eye are referred to as “monocular” HMDs.
HMDs may integrate computer-generated graphics in the user's view of the physical world using a number of techniques. For example, “see-through” HMDs may display graphics on a transparent surface so that the user sees the graphics overlaid on the physical world. “See-around” HMDs, on the other hand, may overlay graphics on the physical world by placing an opaque display close to the user's eye in order to take advantage of the sharing of vision between a user's eyes and create the effect of the display being part of the world seen by the user.